Flashcards in Equations Deck (14)
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1
Clearance of a drug
CL = 0.7 x Vd/ half-life
2
Volume of distribution of a drug
V = D/C
3
Loading dose
LD = Css x Vd
4
Maintence dose
MD = Css x CL
5
Renal clearance
Cx = UV/ P
U = urine concentration of X
V = urine flow rate
P = Plasma concentration
6
Effective renal plasma flow
good going to glomeruli and tubules
Measured using para-aminohippuric acid (PAH)
eRPF= Upah x V/Ppah
eRPF underestimates true renal plasma flow
7
Filtration fraction (kidneys)
portion of blood going to the kidney that is filtered through the glomerulus
FF= GFR/RR
8
Excretion rate (kidneys)
Excretion Rate = V x U
9
Mean Arterial Pressure
MAP = CO x TPR
MAP = 2/3 diastolic P + 1/3 systolic pressure
10
pulse pressure
systolic pressure - diastolic pressure
* proportional to SV
-increase in pulse pressure in hypertension, aortic stiffening, obstructive sleep apnea, and exercise
-decrease with aortic stenosis, cariogenic shock, cardiac tamponade, advanced heart failure
11
Stroke Volume
EDV- ESV
12
Ejection fraction (heart)
EF = SV/EDV
normal: EF >= 55%
-EF decreases in systolic HF
- EF is normal in diastolic HF
13
Renal Blood Flow
RBF= PAH clearance / (1- hematocrit)
PAH clearance = PAH secreted * urine flow/ plasma PAH
Refers to the volume of blood that flows through the kidney per unit time and can be calculated by dividing the renal plasma flow by (1- hematocrit)
14
